Electromagnetic device and circuit therefor



Oct 8, 1935. G. D. MILNE 2,016,448

ELECTROMAGNETIC DEVICE AND CIRCUIT THEREFOR Filed Sept. s, 1953 w 1/51 70,? 6. 0. MIL NE By 2% wm Patented Oct. 8, 1935 UNITED STATES ELECTROMAGNETIC DEVICE AND CIRCUIT THEREFOR George D. Milne, Oak Park, Ill., assignor to vWestern Electric Company, Incorporated, New

York, N. Y., a corporation of New York Application September 8, 1933, Serial No. 688,618

3 Claims. (01. 175-337) This invention relates to an electromagnetic device and circuit therefor and more particularly to an electromagnetic device in which its armature is locked in at least one of its operative positions.

Objects of the invention are to provide a simple, inexpensive and efilcient electromagnetic device in which the armature is mechanically locked in one of its operative positions, and to provide a circuit for utilizing a device of this character.

In accordance with the objects, one embodiment of the invention comprises a pair of oppositely disposed electromagnetic units such as relays having their armatures mechanically interconnected and arranged to be locked alternately in their respective attracted positions, the resilient mounting of each armature serving to retain the other in locked position. The device may be used in a circuit including more than one telephone substation, so arranged that the closing of a part of the circuit to one substation will energize one of the relays and disable the other substation from being used during the use of the first substation.

Other objects and advantages will be apparent from the following detailed description taken in conjunction with the accompanying drawing, wherein Fig. 1 is a front elevational view of the electromagnetic device showing the mechanical locking means in one of the locking positions;

Fig. 2 is a top plan view of the device shown in Fig. l; and

Fig. 3 is a simple wiring diagram of a twostation telephone circuit embodying the invention.

Referring now to the drawing, wherein like reference numerals designate similar parts throughout the views, 10 and H represent cores having base portions l2 with integral lugs I3 extending at right angles with respect thereto for the purpose of securing the electromagnetic device indicated generally at [4 to a frame or suitable support (not shown). Coils I5 and I6 are mounted upon the cores l and II respectively and are connected electrically in the circuit shown in Fig. 3, as hereinafter described. The cores l0 and II have integral heads l1 and I8 projecting outwardly from the coils l and I6 and between which a frame [9 is disposed, the ends of which are secured in any suitable manner to the heads. Armatures 22 and 23, which are U-shaped. in general contour, have their lower ends secured to the upper ends of fiat springs 24 and 25 respectively, the lower ends of the springs being fixed to the bases l2 of the cores ill and H, allowing suflicient clearance between the lower ends of the armatures and the upper surfaces of the bases to permit actuation 5 of the armatures. Any desired arrangement of spring contacts 2'! may be employed. The connecting portions 30 and 3i of the armatures 22 and 23, respectively, are pressed outwardly so that the lugs of the armatures when attracted may be in substantial parallelism with their respective cores, the connecting portions also extending upwardly and having pivotally connected thereto the outer ends of links 32 and 33 respectively. The inner ends of the links 32 and 33 are pivotally connected to levers 34 and 35, respectively. The opposite or lower ends of the levers 34 and 35 are fixed to the outer ends of a shaft 36, which extends through the frame is and is journaled in a bearing 31 integral therewith.

In the wiring diagram (Fig. 3) there are indicated two telephone substations, one of which may be called a first substation and indicated at 40 and the other may be called a second substation and indicated at 4 l. The electromagnetic device I4 is positioned between the substations in the circuit so that it may electrically connect either substation to the main or incoming line, indicated at 42, and to mechanically lock the circuit closed, thereby excluding the other substation from connection to the line. The coils l5 and I6 are connected at a common point to a conductor 43 of the main line 42, which conductor is also connected to a contact member or switch 44.

A contact 45 is electrically connected to one side of a switch as of the substation by a conductor 41, the switch 46 being closed when the receiver is removed. The other side of the 40 switch 46 is connected electrically to the other side of the main or incoming line 42 by means of a conductor 48. A contact 49 is electrically connected to one side of a switch 50 of the subtation 4| by means of a conductor 5|, while the other side of the switch is electrically connected to the main or incoming line 42 through a conductor 52. The coils l5 and I6 are electrically connected to the conductors 41 and 5i, respectively through conductors 53 and 54. When the device [4 is used in a circuit, such as the one just described, the coils I5 and I6 are made with a resistance very high, as compared with that of the substation, and the resistance of each coil may, for example, be of the order of 3000 ohms,

the resistance being introduced in any desired manner, for example, by using resistance wire for the winding.

Upon considering the operation of the device, let it be assumed that the receiver of the substation is removed, closing the switch to complete a circuit from the main line through the conductor 48, the switch 46, conductors 41 and 53, coil I5 and through conductor 43 to the main line 42. The energization of the coil I5 will attract the armature 22, causing it to assume a vertical position, as shown in Fig. 1, moving the link 32 to the right and rocking the lever 34 until the center lines of the pivots at the ends of the link 32 are in the same plane or below the center line of the shaft 36, thus mechanically locking the armature 22 in retracted position. The springs 24 and 25 are so formed that they normally urge their armatures away from each other and into open position. Therefore, the springs 25 will aid the movement of the locking mechanism into the position just described, and thus cooperate with the magnetic force of the coil I5 in moving the locking mechanism into this position. The same is true of the spring 24 when the switch is closed.

When the coil I5 is energized, the switch or contact member 44 is moved to the left into electrical engagement with the contact 45 to directly connect the substation 40 with the incoming line 42. While the circuit is closed for the substation 40, a call cannot be completed from the substation 4| for the reason that the coil I5 has a high resistance as compared with that of the parallel circuit through substation 40, so that the current through substation M has a very low value insumcient to unlock the relay. The operating direct current is, of course, derived from a central battery at the distant end of the subscribers line, the latter having a resistance which may be of the order of 1000 or 2000 ohms.

Furthermore, the party attempting a call over substation 4| cannot listen to the conversation taking place over substation 40, even though a circuit is completed to electrically connect substation 4| with substation 40 and the line. Each substation has a resistance of approximately 43 ohms, whereas each coil I5 and I6 has approximately 3000 chins resistance, making it impossible for the conversation taking place over substation 40 to be heard intelligibly over substation 4|.

After the party has finished his call from substation 40 and has replaced the receiver on the hook, the device remains mechanically locked so that a second call over substation 40 may be made and the device will remain in looking position until a call is made over substation 4| at a time when substation 40 is open circuited. The same is true of substation M in that when a call is made from this substation, the coil I6 is energized, completing a circuit from the incoming line 42, through the conductor 52, switch 50, conductors 5| and 54, through the coil I6 and the conductor 43 to move the armature 23 to the left into locking position and release lever 34 so that the armature 22, forced by the spring 24, will aid in moving the lever 35 into locking position.

What is claimed is:

1. An electromagnetic device comprising a pair of coils, an armature for each coil, a rigid base disposed beneath each armature, resilient members connecting each armature to its base to permit movement of the armatures when attracted by their coils, and means for operatively connecting the armatures together for locking the attracted armature in attracted position and the other in retracted position, said resilient members being flexed to move the armatures in opposite directions so that the resilient members of the unattracted armature will assist in moving the armatures into their locked positions.

2. An electromagnetic device comprising a pair of coils, an armature for each coil mounted for movement, a shaft disposed between the armatures, levers mounted upon the ends of said shaft, and links operatively connecting said levers to said armatures so that the energization of one of the coils will attract its armature to move the link and lever thereof to dead center positions to lock the armatures in position.

3. An electromagnetic device comprising a pair of coils, an armature for each coil mounted for movement, a shaft disposed between the armatures, levers mounted upon the ends of said shaft, and lin is operatively connecting said levers to said armatures so that the energization of one of the coils link and lever thereof to dead center position to lock the armatures in position, said connecting means being such that the energization of the other coil will attract its armature to move its link in the opposite direction, moving the 0 connecting means out of the first locking posirtion and into a second locking position.

GEORGE D. MILNE.

will attract its armature to move the i 

